Citation analysis has been applied in various contexts for different purposes such as impact factors estimation, co-citation pattern analysis, community partitioning, and knowledge visualization etc. We employed graph theory and authoritative sources identification techniques, augmented with visualization tools to discover critical research focuses from the citation graph. The citation graph was built from data retrieved from the CiteSeer database via a querying robot. Two experiments were carried out to identify important research focuses from the citation graph with promising results. Established research focuses as well as new research focuses were successfully identified by the method we proposed and tried. Researchers new to a field may use this method to locate important literature in various fields, which in turn will facilitate their learning and studying.